Etching machine



Feb. 25, 1964 T. HENDERSON 3,122,150

E'I'CHING MACHINE Filed Aug. 3, 1962 8 Sheets-Sheet 1 F l G.- I

fig

- INVENTOR. THOMAS HENDERSON T MO RGAN,FINNEGAN, DURHAM a PINE ATTORNEYST. HENDERSON ETCHING MACHINE Feb. 25, 1964 8 Sheets-Sheet 2 Filed Aug.5, 1962 T0 FIG. 2A

THOMAS HENDERSON MORGAN, FINNEGAN,DURHAM 8 PINE ATTORNEYS Feb. 25, 1964T. HENDERSON 3,122,150

ETCHING MACHINE Filed Aug. 3, 1962 8 Sheets-Sheet 3 INVENTOR.

THOMAS HENDERSON MORGAN, FINNEGAN,DURHAM 8 PINE ATTORNEYS T. HENDERSONFeb. 25, 1964 ETCHING MACHINE 8 Sheets-Sheet 4 Filed Aug. 3, 1962 FlG.-6

FlG.-5

INVENTOR.

THOMAS HENDERSON BY MORGAN, FINNEGAN, DURHAM 6 PINE ATTORNEYS Feb. 25,1964 1-. HENDERSON 3,122,150

ETCHING MACHINE Filed Aug. 3, 1962 8 Sheets-Sheet 5 INVENTOR.

THOMAS HENDERSON BY MQRGAN, FINNEGAN,DURHAM B PINE ATTORNEYS Feb. 25 964Filed Aug. 1962 T. HEN D SON ETCHING MACHINE 8 Sheecs eelc 6 INV TORTHOMAS HEND SON BY MORGAN, FINNEGAN,DURHAM 8 PINE ATTO E"s Feb. 25, 1964HE ND ERSQN I 3,122,150

ETCHING MACHINE Filed Aug. 5, 1962 a Sheets-Sheet 7 XIV I INVENTOR.

THOMAS nsuneason MORGAN,FINNEGAN,DURHAM & PINE ATTORNEY S Feb. 25, 1964-r. HENDERSON 3,122,150

ETCHING MACHINE Filed Aug. 3, 1962 8 Sheets-Sheet 8 AAA HEAD MOTOR masoo A f SPLASH TIMER MOTOR |30A 13s TIMER I INVENTOR.

THOMAS HENDERSON BY MORGAN, FINNEGAN, DURHAM 8 PINE ATTORNEYS UnitedStates Patent Ofifi ce 3,122,150 Patented Feb. 25, 1964 3,122,150 ETCHING MACHINE Thomas Henderson, Locust Valley, N.Y., assignor to PowersChemco, Inc., Glen Cove, N.Y., a corporation of New York Filed Aug. 3,1962, Ser. No. 214,691 Claims. (61. 134-58) The present inventionrelates to etching machines and, more particularly, to machines foretching metallic printing plates. The invention more particularlyconcerns an etching machine for etching arcuately-disposed printingplates.

Heretofore, plates for rotary printing presses, and other pressesemploying printing cylinders, Were etched fiat in the conventionaletching machines. The etched plates, such as electrotype shells, werethen secured to metallic backing pla.es which were curved to fit thepress cylinder. In other instances, the etched plates themselves werecurved onto the press cylinder. In each case, when a plate etched flatwas applied to a curved member, such as a backing plate or the presscylinder, some stretching of the etched plate occurred due to a changein conformation. This stretching of the plate, it will be understood,adversely affected the etched image. Further, in color reproduction itwas extremely difficult to obtain the proper registry of the plates,since there was no way to control this plate stretching, thusnecessitating substantial manual refinishing of the etched plate.

Efforts to overcome this problem have included the attempt to etch theplates in an arcuate configuration. However, such attempts have beenuniformly unsuccessful, since certain portions of the curved plate beingetched persistently received a more sustained splashing of the etchingmordant than other portions thereof, resulting in an undercut plate or aplate that exhibited a high degree of color or dot loss.

General Description The present invention is characterized by a novelplate support and drive mechanism which ensures uniform exposure of thearcuately disposed plate to the etching mordant. The plate to be etchedis supported in curved disposition and spaced from the etchant bath. Theplate is preferably suspended above the etchant and curved about agenerally horizontal axis. The plate support drive means is operative torotate the plate back and forth about its horizontal axis Whilesimultaneously rotating the plate back and forth about a vertical axis.Thus, all portions of plate are substantially exposed equally to thesplashing effect of the mordant, thereby ensuring the proper etching ofthe plate with a minimum of color loss.

In addition, this double rotational movement of the printing plate iseffective to expose all sides of the printing image to the etchant,resulting in a uniform etch. Heretofore, the etchant, impinging againsta curved plate did not contact all sides of the image, producing imagesthat were non-uniformly etched.

Further, means is provided for adapting the plate support for handlingcylin rical and semi-cylindrical plates, and flat plates, such aselectrotype shells, which are curved into arcuate configuration toduplicate their ultimate printing disposition.

Also, in the present invention, there is provided an improved platedrive support cover and hood for the machine which saves machineheadroom while permitting mounting of the machine flush against a wall,eliminating previously wasted floor space. The plate support inciudes asaddle or inverted U-shaped member suspended from the machine cover. Themachine drive mechanism is carried on the top of the cover and the coveris mounted on a carriage arrangement for rolling movement back and forthfrom operative etching position to non-operative plate-loading position.A foldable hood covers the front of the machine during the etchingoperation. This arrangement of tank housing elements provides readyaccess to the plate mounts and replaces the upwardly pivoting machinecover and counterweight employed heretofore.

Another important feature of the present invention is the provision ofmeans for accomplishing uniform peripheral speed for all sizes ofcylindrical arcuate plates. The plate mounting means includes a pair ofopposed, stepped mounting plates to accommodate the various sizes ofcylindrical plates. An adjustable speed drive means is employed torotate each of the various sized plates at a uniform peripheral speed tothus ensure a uniform exposure of the portion of the plate to be etchedto the paddle splash.

Objects It is, therefore, the object of the present invention to providean etching machine for etching printing plates to be used on printingcylinders.

A further object of the invention includes providing in an etchingmachine a novel work holder and drive mechanism for supporting plates tobe etched in curved disposition and simultaneously rotating the plateabout two transverse axes to expose all portions of the plate uniformlyto the mordant.

Another object of this invention is to provide in a paddle-type etchingmachine, a novel work holder for supporting cylindrical andsemi-cylindrically formed printing plates above the level of the etchingbath and rotating the plate back and forth about its major horizontalaxis while simultaneously rotating the plate about its minor verticalaxis.

It is also an object of the invention to provide in an etching machine anovel work holder for simultaneously rotating an arcuately-disposedprinting plate back and forth about its major and minor transverse axes,in excess of 360 in each direction to ensure complete exposure of allportions of said plate to said etching bath.

Another object of the invention is to provide a novel work holdermounting and support means including a rolling carriage for adaptingsaid work holder for moving back and forth from operative etchingposition to nonoperative loading and unloading position.

A further object of the present invention is to provide means foreffecting uniform peripheral speed of each arcuate plate etched.

An added object of the invention is the provision of adjustable drivemeans for the etched plates to effect uniform peripheral speed of eacharcuate plate etched to ensure uniform exposure to the etching mordant.

Other objects and advantages of the invention will be obvious herefrom,or may be learned by practice with the invention, the same beingrealized and attained by means of the instrumentalities and combinationspointed out in the appended claims. 7 V

The foregoing general description and the following detailed descriptionare exemplary and explanatory, but are not restrictive of the invention.

Gf the drawings illustrating, by way of example, a preferred embodimentof the invention wherein like numbers designate like parts:

FIG. 1 is a perspective view partly exploded of an etching machineembodying the present invention.

FIG. 2 is an exploded view of the plate drive mechanism.

FIG. 2A is a continuation of FIG. 2 at line 2A-2A,

FIG. 2.

FIG. 3 is a schematic view of the plate drive mechanism.

FIGS. 4-6 are detailed views of the top cover mounting means.

FIG. 7 is a plan view, partly in section of the machine illustrated inFIG. 1.

FIG. 8 is a detailed view of the saddle rotating means.

FIG. 9 is a sectional view taken along line 9, FIG. 7.

.FIG. 10 is a detailed view, partly broken, of the cylindrical platemounting means.

FIG. 11 is a front view of the etching machine illustrating acylindrical plate supported in the saddle.

FIG. =12 is a front view of the etching machine showing an alternativeform of plate support means.

FIG. 13 is a sectional view taken along line 1313, FIG. 12.

FIG. 14 is a sectional view taken along line 1414, FIG. 12.

FIG. 15 is a sectional view taken along line 1515,

FIG. 13.

FIG. :16 is a detailed view of a plate holding member for the platesupport means of FIG. 12.

FIG. 17 is a schematic wiring diagram for a suitable electrical controlcircuit for the invention.

Referring to the drawings, there is illustrated the preferred embodimentof the invention which includes an open tank 10 adapted to hold asuitable etching fluid. Tank 10 is provided with a cover housing 12,including a movable cover element 14 and hood '16, described more indetail hereinbelow.

To apply the etchant to the printing plate, tank 10 has a plurality ofspaced rotatable splash paddles 18 which pick up the etchant solution intank 10 and forcefully splash or impinge the solution against theprinting plate during the etching operation. Paddles 18 are preferablydriven by associated drive pulleys 19 from a drive belt 21. Suitablearrangements of paddles 18, pulleys 19, and belt 21, and associatedoperating mechanism are disclosed in my co-pending application S.N.113,594, filed May 26, 1961. However, any other suitable means fordriving paddles 18, such as disclosed in Guenst Patent 2,776,512 orEasley et al. Patent 2,669,048, may be employed without adverse effect.

A printing plate P, which may be formed of a suitable material, such aszinc, magnesium, copper, or even plastic, is supported in spacedrelation above paddles .18 by a saddle or inverted U-shaped member 2-0having a preferably horizontally-disposed element-22 and a pair ofspaced downwardly depending arms 24 and 26. Arm 24 is provided with ahorizontally-disposed rotatable hollow stub shaft 28 which is aligned incooperating relationship with stub shaft 30, carried in suitable bearingblock 32 in arm 26. The ends of shafts 2'8 and '36, disposed withinsaddle 20, are each provided with a transverse slot 34.

- To mount printing plate P in saddle 29 for rotation in tank 10 thereis provided a suitable work mounting shaft 36 adapted to be received inthe hollow ends of opposed stub shafts 28 and 30. Shaft 36 has, at eachend thereof, a transverse pin 38 which fits snugly into slot 34 of itsassociated stub shaft, holding shaft 36 in generally horizontaldisposition above paddles 18 in tank 10, as shown in FIG. 2.

To permit mounting of shaft 36 in operative plate supporting position,stud shaft 30 is freely supported in arm 26 for movement back and forththerein. When plate P on shaft 36 is to be mounted in saddle 20, shaft30 is moved away from stud shaft 28. This allows one end of shaft 36 tobe easily inserted into shaft 28 with pin 38 seated properly in itsassociated slot 34 on shaft 28. With shaft 36 so seated, stud shaft 36is returned toward shaft 28 and into engagement with its associated endof shaft '36. The other pin 46' of shaft 36 is properly seated in slot34 of shaft 39, and plate P is thus secured in proper position to beetched.

To ensure against inadvertent movement of shaft 30, there is provided apivotable latch member 41, which is normally disposed against stop 42and in the path of travel of shaft 30. Latch 41 limits movement of shaft31} until pivoted away from stop 42 by the machine operator.

Drive Mechanism To rotate shaft 36 and plate P in tank *111, the end ofstud shaft 28 passing through arm 24 and disposed on the side of arm 24,remote from shaft 36, is provided with a sprocket 4-4 driven by anendless chain 46. Chain 46, in turn, is trained about a drive sprocket48 aflixed to one end of a shaft 50 supported in bearing block 52 on theunderface of top member 22 of saddle 20.

The other end of shaft 50 has aifixed thereto a pinion 54- which is inmeshing engagement with pinion 56 carried at one end of a vertical driveshaft 58. Shaft 58, in turn, is concentrically disposed within a hollowvertical tubular member 60 fixed to and supporting saddle 26.

Sleeve 66 passes through bearing housing 62 on support plate 64 mountedon cover element 14 and is provided at its end, remote from saddle 20,with a spur gear 66. Gear 66, in turn, is in meshing engagement withlarger spur gear 68. It will be understood that rotation of spur gear 68thus effects rotation of gear 66, and sleeve 60, rotating saddle 20 inthe direction of the arrows A and B, FIG. 3.

To effect rotation thereof, gear 68 is axially mounted on one end of adrive shaft 70. The other end of shaft 70 is connected to atorque-limiting friction clutch 72 which effects a driving connectionbetween shaft 70 and one end of an oscillating lever 74. The other endof lever 74- is pivotally connected to an end of-link 76, whose otherend is pinned to crank arm 78.

Crank arm 78 is secured to and rotates with the output shaft 80 of anglegear unit 82. The input shaft 84 of gear unit 82, in turn, is connectedto the output shaft 86 of a suitable non-reversible gear reduction motor88. As shown best in FIG. 2, gear unit 82 and motor 88 are mounted on asupport plate 90. Plate 90, at the end adjacent motor 88, is fixeddirectly to cover element 14 which the other end of plate 90 is securedto plate 64.

Shaft 58, axially disposed within sleeve 60, is rotatably accommodatedin spur gear 66, passing through bearing housing 92 on another supportplate 94. The end of V shaft 58, remote from saddle 20, is provided witha spur gear 96 in meshing engagement with spur gear 98 aflixed to adrive shaft 100. The lower end of shaft 100 is suitably seated inhousing 92, while adjacent its upper end, shaft 16% is provided with aworm gear 102. A torque-limiting friction clutch 104 is connected withthe upper extremity of shaft 100. Clutch 104 is preferably similar inconstruction and operation to clutch 72.

To rotate worm gear 102, there is provided in meshing engagementtherewith a worm 106 connected at one end to the output shaft 168 of asuitable adjustable speed reversing motor 110. The other end of worm 106is suitably supported in a bearing plate 112, fixed to hearing housing92. Motor 110 is mounted on plate 94, in turn, secured at the endthereof adjacent motor 110 to plate 90. The other end of plate 94 iscarried by support plate 64, as shown in FIG. 2.

It will be understood that actuation of motor 110 effects rotation ofworm 1136, gear 104, shaft 160, gears 96 and 98 and, hence, shaft 58.Since shaft'58 is ultimately in driving relationship with stud shaft 28,rotation of shaft 58 rotates'shaft 36 and printing plate P in thedirections of the arrows, C and D, FlG. 3. Motor can be replaced, ifdesired, by a direct current motor with an alternating current variablevoltage.

Cover and Hood Cover housing 12 comprises a movable cover element 14 anda hood 16. Hood 16 includes three interhinged sections 114, 116 and 118.Section 114 is adapted to be normally aligned with cover element 14 andis hingedly connected to the leading edge of element 14 by hinge member13. Sections 116 and 118 are adapted to be normally disposed in verticalrelationship against the front of tank 10. Handle 120 facilitatespivotal movement of sections 114, 116 and 118 to provide access to tank10.

To facilitate mounting or removal of plate P in saddle 20, cover element14 is mounted for travel back and forth on tank 10 in the direction ofarrows W, FIG. 1. Tank 10 is provided at each side thereof adjacentcover 14 with a track 120. Cover element 14 is mounted for travel alongtracks 120 by means of a carriage-like arrangement including fourvertically-disposed wheels 122, one of which is rotatably fixed to cover14 at each corner thereof. Four horizontally-disposed casters 124, oneadjacent each wheel 122, assist in adapting cover 14 for back and forthmovement on tracks 120.

Electrical Control System FIG. 17 discloses a suitable schematic wiringdiagram for controlling the various drive mechanisms of the subjectinvention. As disclosed in my aforementioned co-pending application S.N.113,594, there is provided a constant, low-speed agitator motor 126 formaintaining the etchant bath in thoroughly mixed condition in tank 10.Likewise, there is provided a variable speed splash motor 128 forrotating paddles 18 at their etching speed. Timer motor 130 and timermotor switch 130A and relay 132 interconnect motors 126 and 128 toselectively actuate either motor 126 or motor 128. An agitatorstart-stop switch 134 and cover safety switch 136 may also beconveniently included.

In the present invention, motor 88 is electrically connected in parallelwith splash motor 128 for simultaneous actuation therewith. Reversiblemotor 110 is also connected in parallel with motors 88 and 128. Timermotor 138 is provided for effecting reversal of motor 110 at the propertime in the sequence of machine operations. Timer motor 138 is acommercially available unit for controlling reversible motors such asmotor 111). Timer earn 139 of motor 138 is in engagement at all timeswith either contact 149 or 142 of motor 110, as it rotates on timershaft 137. This alternately effects rotation of motor 110 first in onedirection and, then, in the opposite direction.

While the control system of FIG. 17 relates to the system disclosed inmy aforementioned pending application, other systems can be employedwith equal facility and without adverse effect.

Plate Mounting Means The present invention is adaptable for use witharmate plates (generally called segments in the trade); cylindricalplates and flat plates which are eventually to be used on a curvedprinting cylinder. To mount these members on shaft 36, a variety ofmeans is provided.

To mount plate cylinders 143, such as illustrated in FIG. 11, there isprovided on shaft 36 a stepped end plate 144. Lock collar 146 limitsaxial displacement of plate 144 along shaft 36, while step 145 isadapted for positioning in contact with the inner periphery of the platecylinder 1 .3. A pair of cooperating, stepped end plates 148 and 149 areprovided for the opposite end of the plate cylinder 143. Plates 148 and149 are preferably semicircular and spaced apart in plate cylinder 143to form a center opening 159. A cap plate 6 152 is axially disposed onshaft 36 and provided with a pair of spaced wing bolts 153 and 154threaded for travel in end plates 148 and 149, respectively. Cap 152also includes spacer members 156 for engaging the edges 151 and 155 ofplates 148 and 149 which define opening 150 and exerting radial pressureon plates 148 and 149 as cap 152 is urged thereagainst through wingbolts 153 and 154 and locked in position on shaft 36 by lock collar 158.The camming action of members 156 ensures that plates 148 and 149 willremain seated against the end of plate cylinder 143 during the etchingoperation.

To accommodate various diameters of plate cylinders 143, end plate 148is provided with a plurality of steps 148A adapted to fit the standardsizes of plate cylinders. In like manner plate 144 includes a pluralityof steps 145A to accommodate the other standard sizes of plate cylindersother than the size accommodated by steps 145.

When plate segments 160 are to be etched, end plates 144 and 148 areremoved and replaced by a series of spaced annular supports 162, eachcomprising an annular shell 164 braced by cross-struts 166 and mountedconcentrically on shaft 36, as shown in FIG. 12, and locked thereon bylock nut 168.

Each shell 164 is provided with two opposed circumferential slots 170and 172 and two opposed longitudinal slots 174 and 176. Each slot, 178,172, 174 and 176, is adapted to accommodate therein a locking member 178comprising an inner plate 180 and an outer plate 182. Bolt 184 and wingnut 186 interconnect plates 180 and 182.

A segment 16%, is generally supported along the bottom portions of two,three, or four supports 162 depending on the size thereof. FIG. 12illustrates a segment supported on three supports 162. It will beunderstood that the spacing between supports 162 correspondssubstantially to the conventional lengths of printing segments.

Each longitudinal slot 174 and 176, adjacent the side edges 159 and 161of segment 160, is provided with a locking element 178. Also, eachcircumferential slot 170, adjacent edges 159 and 161, is so providedwith a locking member 178. Edges 159 and 161 are disposed between outerplate 182 of the locking element 178 and the outer face of shell 164, asshown in FIGS. 15 and 16. Wing nuts 186 are tightened firmly, clampingsegment 168 against shell 164 during the etching operation.

Slot 172 is provided in the event two segments 160 are to be etchedsimultaneously. In such event, a second plate 166 is secured over thetop of supports 162 with locking members 178 in longitudinal slots 174and 176 being operative to clamp both segments 160 in common to itsassociated shell 164.

The foregoing are two convenient means for mounting arcuate printingplates for etching. Other means of mounting such plates may be employedwithout adverse effect.

Operation In operation, at the start of the etching operation, themachine operator folds sections 114, 116 and 118 of hood 16 back on eachother to provide access to tank It). The appropriate etching mordant;such as, nitric acid, is placed in tank 10, together with any desiredetching additives. It is desirable for the operator to depress switch134 to effect complete dispersion and emulsiiication of the etchingsolution.

When plate P is ready to be etched, it is mounted on shaft 36 by meansof end plates 144 and 148 or annular supports 162, as describedhereinabove. With plate P secured in proper position on shaft 36, coverelement 14 is rolled toward the front of tank 10 to move saddle 20 intoposition for easy access and mounting therein of plate P. Stud shaft 311is then moved out of saddle 20 so that one end of shaft 36 can bereadily inserted in shaft 28 and properly seated therein. Shaft 30 isnow returned into seating engagement with the other end of shaft 36 andlocked in such position by latch 40. Cover element 14 is moved away fromthe front of tank It? to the posit-ion shown in FIG. 1. Plate P is nowready for the etching operation.

To start the etching operation, hood 16 is returned to operativetank-covering position (see FIG. 1). This closes safety switch 136,completing a circuit energizing splash motor 128. Simultaneously, acircuit is completed actuating motors 88 and motor 110 through timermotor 138.

Upon actuation, motor 88 rotates its output shaft 86 to effect rotationof shaft 80 of unit 82. This, in turn, rotates crank arm 78, link 76,and lever 74 which, through clutch 72 and shaft 70, turns spur gear 68.

It will be understood that, because of the arrangement of crank arm 78,link 76, and lever 74-, spur gear 68 is rotated first in one directionand, then, in the opposite direction, even though output shaft 86 ofmotor 88 rotates continuously in the same direction.

The reversing rotation of gear 68 is transmitted to meshing gear 66 and,hence, to tubular shaft 58 and saddle 28 to rotate saddle 20 in thedirection of the arrows E and F, FIG. 3.

To ensure complete randomness and non-uniform exposure of the plate P tothe etchant, members 78, '76 and 7 are so dimensioned and arranged, andgears 66 and 68 are so proportioned, that the rotation back and forth ofgear 68 effects rotation of gear 66 and saddle 20 somewhat more than onecomplete revolution in a particular direction.

Simultaneously, with the back and forth rotation of saddle 20 throughmotor 88, motor 110 and timer 138 are energized to rotate plate P.Energizing of motor 110 rotates its output shaft 108 and worm 106,which, in turn, effects rotation of worm gear 102, shaft 10% and spurgears 98 and 96. Since gear 96 is fixed to shaft 58, rotation of gear 96turns shaft 58 which, in turn, turns shaft 50 through pinions 56 and 54.Rotation of shaft 5% is then transmitted through sprockets 43 and 44 andchain 46 to shafts 28 and 36 to rotate plate P back and forth in saddle29.

It will be understood that as motor 110 is reversed through timer 138,its associated drive mechanism is also rotated first in one directionand, then, in the opposite direction to completely expose all portionsto the etchant in tank 10. To ensure random, non-uniform plate exposure,gears 96 and 93 are so dimensioned and proportioned that rotation backand forth of gear 98 by motor 110 effects rotation of gear 96 and,hence, shaft 38 and plate P somewhat more than one complete revolutionin a particular direction.

Motors 88 and 110 and their associated drive mechanisms remain actuatedrevolving saddle 20 and plate P back and forth in tank until thecompletion of the etching operation as determined by timer motor 13%When the etching operation is completed, timer 139, through relay 132,interrupts the circuit to motors 88, 119 and 128 while re-energizingmotor 126. With the saddle 20 and plate P stopped, and the paddles 18revolving at their slower agitating speed, the operator re-opens hood16, slides cover element 14 toward the front of tank 10, and removesshaft 36 and etched plate P from saddle 20 until the next etchingoperation.

Thus, there is disclosed a simple, efiicient device for quickly andeasily etching curved plates without the adverse eifects heretoforepresent. The random rotation of the plate to be etched co-acting withthe random rotation of the plate support about an axis transverse to theplate rotation ensures overall non-uniform exposure of the plate to theetchant, minimizing the danger of undercutting.

What is claimed is:

1. In an etching machine for etching printing plates, the combination ofa tank for holding a supply of etching fluid, means for vigorouslyapplying said fluid against said plate -to be etched, means forenclosing said tank and fluid, a plate holder revolvably supported insaid tank and disposed above the level of said fluid, means for ro-ttatably mounting at least one of said plates in said plate holder, andmeans for revolving said plate holder about a first axis and means forrotating said plate mounting means about a second axis angularly'related to said first axis.

2. The device as defined in claim 1, wherein said first and second axesare substantially transverse, and including means for effectingsubstantially simultaneous rotation of said plate holder and platemounting means.

3. The device as defined in claim 1, including means for periodicallyreversing the direction of rotation of said plate holder and said platemounting means during the etching operation.

4. An etching machine for etching printing plates comprising a tank forholding a supply of etching fluid, a plurality of elongated paddlemembers, means mounting said paddle members for rotation in said tank,operating means for rotating said paddles for splashing said etchingfluid against said plates to be etched, housing members for enclosingsaid tank and fluid, a plate holder rotatably supported in said tank,and disposed above the level of said fluid, said plate holder beingadapted to support said plates in a generally curved configuration,means for totatably mounting said plate in said plate holder, the axisof rotation of said plate holder being generally at right angles to theaxis of rotation of said plate mounting means, means for effectingsimultaneous rotation of said plate holder and said plate mountingmeans, and timing means for periodically reversing the direction ofrotation of said plate holder and plate mounting means during theplateetching operation.

5. The invention as defined in claim 4, wherein said plate mountingmeans and said plate holder each rotate in excess of 360 beforereversal.

6. The invention as defined in claim 4, including separate drive meansfor said plate holder and for said plate mounting means, and anelectrical operating circuit interconnecting said separate drive means.

7. In an etching machine for etching arcuate printing plates, acombination of a tank for holding etching fluid paddles rotatablysupported in said tank for impinging said fluid against said plate to beetched, enclosure means for said tank and said fiuid, a saddle memberrotatably supported in said tank and in spaced relation above the levelof said fluid for holding said plate, a shaft rotatably supported insaid saddle, means for mounting said plate in curved configuration onsaid shaft, first gear means for rotating said saddle about a generallyvertical axis, second gear means for rotating said shaft in said saddleabout a generally horizontal axis, operating means for said first gearmeans, operating means for said second gear means, and meansinterconnecting said operating means for effecting simultaneous rotationof said saddle and shaft at the start of the etching operation, wherebysaid curved plate is uniformly exposed to said etching fluid.

8. The invention as defined in claim 7, wherein said first operatingmeans includes a motor, a rotatable crank arm, means effecting'a drivingconnection between said crank arm and said motor, a link member havingone end thereto pinned to said crank member, an oscillating lever pinnedto the other end of said link member, and means interconnecting the freeend of said oscillating lever to said first gear means, whereby rotationof said crank member effects a back and forth movement of saidoscillating lever to reverse the direction of said first gear means; andwherein said second operating means includes an electrical motor, a wormdriven by said motor and in driving engagement with said second gear,and a timer member for reversing the direction of said electrical motorto reverse the direction of rotation of said worm and associated gearmeans.

9. The invention as defined in. claim 1 wherein said plate mountingmeans includes elements for accommodat- 3,122,150 9 ing arcuate platesof various sizes and means for revolving said various-sized plates at auniform peripheral speed during the etching thereof.

References Cited in the file of this patent UNITED STATES PATENTS Theinvention as defined in claim 3 m the 993,503 Br ov vnmg May 30, ricalmo or for said second operating means indudcs 1, 1 Hilliard Aug. 22, 1means for adjusting the speed thereof whereby the Pg 1,836,444 e n Dec.15, 921 p l sp ed of said plates is controlled t eff t 1,850,968 M rt nMar. 22, 19.. form peripheral speed of plates of Various-sized curved2,824,029 y F 18, 195 Configurations, 3,078,857 Gu L Feb. 26, 196.7

1. IN AN ETCHING MACHINE FOR ETCHING PRINTING PLATES, THE COMBINATION OFA TANK FOR HOLDING A SUPPLY OF ETCHING FLUID, MEANS FOR VIGOROUSLYAPPLYING SAID FLUID AGAINST SAID PLATE TO BE ETCHED, MEANS FOR ENCLOSINGSAID TANK AND FLUID, A PLATE HOLDER REVOLVABLY SUPPORTED IN SAID TANKAND DISPOSED ABOVE THE LEVEL OF SAID FLUID, MEANS FOR ROTATABLY MOUNTINGAT LEAST ONE OF SAID PLATES IN SAID PLATE HOLDER, AND MEANS FORREVOLVING SAID PLATE HOLDER ABOUT A